Marine Safety Alert with corrections and additional information
The U.S. Coast Guard has issued updated Marine Safety Alert on the use of surge protective devices on board vessels that corrects an alert on this subject issued earlier this month and adds additional information.
We’ve all seen them and used them. Surge protective devices (SPDs), more commonly known assurge protectors or power strips help protect our expensive electronic devices from being damagedfrom excessive currents and allow us to simultaneously deliver power to multiple devices. This safetyalert addresses the use of certain electrical protection devices onboard vessels and the inherent risksthey may cause. Most commercially available SPDs are designed for use ashore and will interruptonly the hot conductor when a surge occurs. What does that mean for the ship owner/operator? Itmeans that while these devices may provide protection in our homes and offices, these same devicesmay be a fire risk onboard vessels.
A marine casualty investigation of two separatestateroom fires onboard a U.S. Flag Containership revealed that the sources of the fires wereattributed to the use of SPDs plugged into alighting circuit. It was discovered that a groundhad developed on another circuit that wasconnected to the same distribution panelproviding power to the staterooms. This groundcreated an imbalance of voltage between thetwo power conductors supplying the SPDswhich caused excessive currents, overheating,and subsequently, a fire. In this instance, evenif the SPDs automatically tripped as designed,only one power conductor would have beensecured while the other would continue toprovide power, possibly shorting to the device’s ground wire and the structure of the vessel.For shipboard applications, it is critical for a device to interrupt both power conductors.
The Coast Guard recommends that vessel Owners, Operators, Class Society Surveyors, Insurers,and other inspection personnel examine the risks associated with the use of SPDs aboard theirvessels, and if necessary ensure their organizations have policies and procedures relating to theiruse. Vessels should have defined procedures for checking the condition and grounding capabilitiesof personal/portable electrical equipment, and trained shipboard personnel should be assigned tocheck and approve all SPDs in use or brought on board for compatibility with the vessel’s electricaldistribution system prior to use. Routine checks of switchboard and distribution system 120 VACground detection systems are necessary to detect the presence of grounds that may cause similarcircumstances with non-marine type SPDs. These recommendations are not mandated rather just anadvisory based on lessons learned from the casualty.
Additional Technical Information:
“This safety alert only applies to vessels with alternating current power systems and may be most likely applicableto larger industrial and commercial vessels. It relates to different manners in which power is generated,transformed and supplied throughout the vessel.” There is no official Underwriters Laboratory standard for Marine Surge Protective Devices despite numerousretailers advertising “UL Marine 1449.”
The recommendations on page one of this document remain. Ideally, if there is excessive use of power strips onboardthere may be a need to consider the installation of additional permanent components such as distribution panels,breakers, cabling or receptacles. An SPD should be
only permitted for use onboard once approved by a trained crewmember,
removed from service if it is hot to touch,
unplugged when not in use,
regularly inspected for damage or wear,
limited to one SPD per single duplex receptacle outlet and never daisy chained,
prevented from use in excessively humid or moist environments,
provided air circulation and not covered with carpet or other items, and
checked to ensure that all plugs are fully engaged.
The primary concern of this alert is to ensure electrical protection devices such as SPDs operate correctly with themanner in which the 120 volt receptacle circuitry onboard the vessel is wired. Receptacle circuitry may be wired in Deltaor WYE configurations.
For more information, be advised on the marine safety alert on surge protectors.
Source: USCG